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Journal ArticleDOI

Research and Technical Trend in Nuclear Fusion in Japan

01 Dec 2017-Vol. 4, Iss: 4, pp 16-23

AboutThe article was published on 2017-12-01 and is currently open access. It has received 1 citation(s) till now. The article focuses on the topic(s): Nuclear fusion.

Topics: Nuclear fusion (56%)

Summary (2 min read)

1. Introduction

  • In 21th century, multi-polarity of the world economy arises such as BRICs (Brazil, Russia, India and China) or developing countries in Asia and Africa.
  • For economic efficiency & sustainable economic growth, it shows a contradiction that pursuing economic growth causes the destruction of environment or the disparity on the other side of earth.
  • This type of partnership or agreement have been established between many countries because the trilemma cannot be solved by one nation.
  • Second, the history and uniqueness of nuclear fusion are described.

2. Technology for Energy Issue

  • Two third of electricity in the world comes from thermal power plant2).
  • Solar power, wind power, water power, wave power, geothermal power and biomass are one of them.
  • It is beneficial for countries like Japan where energy resources are poor.
  • The incident in Fukushima exposed the vulnerability in handling nuclear power plant even in one developed country Japan.

3. Nuclear Fusion Energy

  • The nuclear fusion energy, which described in this paper, is quite different from the technology used in the current nuclear power plants.
  • Plants for the deuterium separation already exist all over the world.
  • Technology for the blanket has been a key issue and intensively studied.
  • Therefore, separation between hot plasma and superconducting coils are to be realized.
  • In a fusion power plant, materials and equipment inside the reactor are to be radioactivated by energetic neutrals from fusion reaction.

3.1 History of Fusion Research and Development

  • The stream of fusion energy research started from late 1920s.
  • After this discovery, research and development toward nuclear fusion power, which would be the ultimate solution for energy crisis, has been carried out since the 1940s.
  • Tokamak is another type of plasma confinement, which twists magnetic field by producing current inside of plasma.
  • ITER will test the feasibility of fusion power plant.

4. Nuclear Fusion Trend in Japan

  • Fusion energy trend in Japan will be presented.
  • In Fig. 2 (B)11), the need for government involvement in different fields is shown.
  • Along with the reduction of budget, working population in this field has been also decreasing.
  • The result includes published documents from all over the world.
  • Even though the budget and working population on nuclear fusion are in decrease in Japan, it shows research activities on international scale has been intensively promoted toward the construction of ITER and the commercialization of nuclear fusion power plant14).

5. Conceptual Reactor Design

  • The authors have discussed the trend of fusion technology, focusing on tokamak type of plasma confinement of plasma.
  • Since 1960s to present, 50 conceptual power plant design studies have been conducted worldwide16).
  • In ref. 16, detailed explanations are denoted.
  • Tokamak type has been frequently developed as a whole.
  • Compactness can directly contribute to the cost-effectiveness since larger device gives rise of construction cost.

6. Summary and Discussion

  • Research and development trend in tokamak fusion energy has been investigated in this paper.
  • As for Japan, the government regards fusion energy as one important energy policy.
  • 10) Japan Ministry of Education, Culture, Sports, Science, and Technology, “Current state of nuclear fusion research development in Japan”, The 13th Atomic Energy Commission (2014).

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九州大学学術情報リポジト
Kyushu University Institutional Repository
Research and Technical Trend in Nuclear Fusion
in Japan
Yoneda, Ryota
Interdisciplinary Graduate School of Engineering Sciences, Kyushu University
https://doi.org/10.5109/1929677
出版情報:Evergreen. 4 (4), pp.16-23, 2017-12. Green Asia Education Center
バージョン:
権利関係:

EVERGREEN Joint Journal of Novel Carbon Resource Sciences & Green Asia Strategy, Vol. 04, Issue 04, pp. 16-23, December 2017
Research and Technical Trend in Nuclear Fusion in Japan
Ryota Yoneda
1
1
Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Japan
E-mail: yoneda@triam.kyushu-u.ac.jp
(Received August 16, 2017; accepted October 16, 2017).
The energy shortage in near future has been a hot topic. Many countries and companies have
introduced clean energy technologies such as solar, wind and water. In general, a large part of
electricity comes from fire power plant. It is almost impossible to replace all of the fire plants into
clean energy power plants since they cannot provide electricity stably. Nuclear fusion power has
been considered as an ultimate solution for energy crisis and has been developed since the 1950s.
Now it has come to the phase of practical power generation. A large construction of fusion reactor is
in progress in France as an international cooperation. In this paper, we investigate Japan’s R & D
trend of nuclear fusion especially in tokamak reactor by making comparison with other countries to
show future contribution to fusion society.
Keywords: nuclear fusion, energy diversity, magnetic confinement fusion.
1. Introduction
In 21th century, multi-polarity of the world economy
arises such as BRICs (Brazil, Russia, India and China) or
developing countries in Asia and Africa. Huge
consumption of energy resources has been a critical issue
to realize sustainable development under the conditions
that not only for inhibiting the global warming but also
constraining energy resources such as petroleum and
water. As a solution of this state, 3E-vision has been
discussed
1)
: Energy security, Environmental protection
and Economic efficiency & sustainable economic growth.
Those concepts enclose many aspects. For energy security,
it stands for the shortage of energy, resources & food, the
inequality in distribution and economic refugee. For
environmental protection, it indicates the global warming,
the destruction of forest, the destruction of ozone layer,
marine pollution and acid rain. For economic efficiency &
sustainable economic growth, it shows a contradiction that
pursuing economic growth causes the destruction of
environment or the disparity on the other side of earth. To
solve this trilemma is extremely difficult and requires
approach from the various fields. In Asian countries,
which expected as the center of the future economic
development, partnership between Japan and the ASEAN
countries toward the realization of sustainable society has
been established. This type of partnership or agreement
have been established between many countries because
the trilemma cannot be solved by one nation. International
cooperation becomes much more important to push
forward those problems in a strategic way.
In this paper, we focus on technological aspects to solve
the expected energy crisis in near future. Specifically, it
discusses the research and technical trend in nuclear
fusion. First, technological aspects for energy issues are
summarized and categorized to show differences between
them. Second, the history and uniqueness of nuclear
fusion are described. Then, the research and development
trend in nuclear fusion is shown. Finally, results are
summarized and discussion is given.
2. Technology for Energy Issue
Two third of electricity in the world comes from
thermal power plant
2)
. It is well-known that the deposit of
coal, petroleum and natural gas is finite and they are going
to be depleted in near future. The amount of reserve and
the estimated time for the depletion are controversial,
however, the coming energy crisis is inevitable.
In recent days, so called “Renewable Energy” is getting
attention and should be mentioned. The definition of
renewable energy is broad, it means basically the energy
resources that always exist and produce no greenhouse gas
especially CO2. For example, solar power, wind power,
water power, wave power, geothermal power and biomass
are one of them. We do not go into detail on these
technologies but let us summarize here. They are clean in
terms of greenhouse gas and radioactive material
production. Introduction of renewable energy power plant
increases the energy self-sufficiency rate. It is beneficial
for countries like Japan where energy resources are poor.
However, the main problem for renewable energy is that
the stable supply is difficult because many of them
strongly depend on climate and seasons. Solar cell, for
example, can only operate during sunny day-time to
generate electricity. Water power can supply electricity
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EVERGREEN Joint Journal of Novel Carbon Resource Sciences & Green Asia Strategy, Vol. 04, Issue 04, pp. 16-23, December 2017
constantly but possible locations are limited as it has to be
close to mountain sides. For these limitations, it is not
realistic to replace all of fire plant into renewable power
plant. In Japan, nuclear power generation had been
promoted until the tragic earthquake hit the east Japan in
2011. A huge tsunami destroyed nuclear power plant in
Fukushima, causing melt-down and a massive release of
radioactive substances. Japanese government had no
choice but revises its policy of energy. The incident in
Fukushima exposed the vulnerability in handling nuclear
power plant even in one developed country Japan. In the
present circumstances, Japan runs fire plants to
complement the nuclear power plants.
3. Nuclear Fusion Energy
The nuclear fusion energy, which described in this
paper, is quite different from the technology used in the
current nuclear power plants. It should be noted briefly
how it works to avoid misunderstandings. The principle
used in general nuclear power plant is called nuclear
fission. In fission power, we use Uranium 235. As a
neutron hits Uranium, its nucleus separated into two
nucleuses. When this reaction occurs there exists a
difference in total mass between before and after the
reaction. This difference of total mass is released as
energy following the famous equation by Einstein
(E=mc
2
). The fission reaction also produces few neutrons
and they hit other Uranium. By discreet controlling of
reactions under the operational range enables a continuous
production of energy. Fission requires careful control to
prevent runaway of reactor and it is famous that tragedies
happened in Chernobyl and Fukushima. In contrast,
nuclear fusion uses light atoms such as deuterium and
tritium (they are the isotopes of hydrogen). In the reaction
between deuterium and tritium (D-T reaction), it produces
helium atom and one neutral. There is also a mass
difference before and after, which is equivalent to the
energy released. The concept of fusion power plant is the
utilization of this fusion reaction. The current state of
fusion power plant is on the phase of practical generation
of electricity. The theory of fusion is well-developed but
there still remain a lot of technical issues to solve.
The uniqueness of nuclear fusion energy basically can
be described as following
3)
: (1) The deuterium as fuel
exists 1cc within 3L of usual water. Therefore, there is no
resource shortage for nuclear fusion. (2) It produces no
waste that contaminates environment such as CO2 and
there is no requirement of material treatment for ultra-long
term. (3) The nuclear fusion reaction at the reactor core
can be controlled safely. These three points are often
mentioned when making a comparison with nuclear
fission. Therefore, let us consider more in detail here. For
(1), power generation output of 100 million kW with D-T
reaction requires 200g of deuterium per day. 150 ppm of
hydrogen isotope within whole amount of water in the
ocean is deuterium, therefore we can say deuterium
deposit is inexhaustible. The question is how to separate
it from water practically. There is a misunderstanding that
the separation of water by electrolysis takes huge amount
of energy and this makes fusion impossible to generate net
of energy at all. It is true that to divide water by
electrolysis and proceed isotope separation consume great
deal of energy, however, water molecular itself has a slight
difference in chemical property whether it contains
normal hydrogen or deuterium. Making use of this
difference, it is possible to separate deuterium efficiently.
Plants for the deuterium separation already exist all over
the world. Especially, in Canada, it has been well-
developed and commercialized. For (2), one should
mention that radioactive materials can be produced during
the operation of fusion reactor. Tritium as fuel is
radioactive and it is difficult to produce in terms of cost.
Therefore, it can be produced by nuclear reactions
between lithium and neutrals from fusion reaction inside
the blanket. The blanket is a device located inside of
fusion reactor that contains lithium to produce tritium and
inject it as fuel into fusion plasma. The point is that only
few percent of the injected fuels (deuterium and tritium)
can make fusion reaction so that the rest would be released
as exhaust emission. Tritium has mobility and it must be
carefully handled. Another radioactive material can be
also produced that energetic neutrals from fusion plasma
make plasma facing components radioactive. This kind of
radioactive is solid state and low level that it is relatively
easy to handle compared with radioactive from fission
power reactor. Technology for the blanket has been a key
issue and intensively studied. Finally, about (3), we see the
reason why there is no runaway with fusion reactor. In
magnetic confinement of fusion plasma, the possible
operation range for fusion reaction is very narrow. Such
required temperature and density of plasma are sensitive
for fuel injection or impurities. If there is an error in
operation such as excess supply of fuel, it cannot sustain
the reaction conditions. Then, it terminates automatically.
Of course, a sudden termination can cause a damage to the
reactor so that safe operation is also of importance. In
these manner, nuclear fusion energy is not perfectly clean.
Even though, the amount of energy that it can produce
would be enormous. As one alternative, nuclear fusion
should be taken account.
What makes fusion so difficult? It will be also
mentioned in next section that for fusion reaction both
high performance plasma and high confinement of plasma
are required. These conditions are against each other, such
high-performance plasma with high temperature and
density tries to escape from confinement area. For this
purpose, a large construction of fusion device is needed to
sustain fusion reaction by applying large amplitude of
magnetic field. Note that for D-T reaction, temperature
more than 100 million Celsius is necessary. Not only for
making fusion reaction, we also need to consider:
electricity generation system, materials with heat-
resistance, fuel recycling, safety operation and so on.
There are mainly 11 technical considerations for
- 17 -

Research and Technical Trend in Nuclear Fusion in Japan
realizing a fusion tokamak reactor: superconducting coils,
blanket, divertor, plasma heating & current drive, physics
& simulation, core plasma physics, fusion fuel system,
materials of reactor, reactor safety design, occupancy rate
& maintainability and measurement & control
4)
. Here,
brief explanations for some terminologies are given. First,
superconducting coil is a specialized coil that can produce
strong magnetic field. The superconducting condition
makes metal materials no electrical resistance that high
current can generate much higher magnetic field. For this
condition, extreme cooling of coil is necessary. Therefore,
separation between hot plasma and superconducting coils
are to be realized. This poses technical difficulties and a
large complex construction is indispensable. Second,
divertor is a part of tokamak that exhaust helium or
impurities from reaction to sustain long-duration tokamak
operation. It is also the area where the strongest heat load
comes due to magnetic field configuration. Since the
expected heat load in fusion reactor would be 10 MW per
m
-2
, which is an order of magnitude larger than fission
reactor. Maintainability of reactor should be also
mentioned. In a fusion power plant, materials and
equipment inside the reactor are to be radioactivated by
energetic neutrals from fusion reaction. Maintenance by
human will be impossible so that remote maintenance by
machines are planned.
3.1 History of Fusion Research and Development
The stream of fusion energy research started from late
1920s. R. Atkinson and F. G. Houtermans suggested that
the energy source of stars is some sort of nuclear
reactions
5)
. The quantitative evaluation of nuclear fusion
were first revealed in late 1930s. After this discovery,
research and development toward nuclear fusion power,
which would be the ultimate solution for energy crisis, has
been carried out since the 1940s. An important note on
1950 is that a famous astronomical scientist L. Spitzer at
Princeton University first came up with the idea of
“stellarator”, which confines hot plasma by applied
twisted magnetic field
6)
. First, fusion research was
classified in the US during the cold war, but at 2nd UN
Atoms for Peace Conference in 1958, it was declassified
because researcher in the US and others found the
realization of fusion was much difficult than expected
7)
.
As a consequence, research and development in fusion has
initiated based on international cooperation since then. In
the 1960s, fusion research suffered its poor confinement
of plasma. However, things changed when Tokamak T-3
at the Kurchatov Institute reached 1keV (more than 10
million degrees) electron temperature which is much
greater than the stellarator in 1968
8)
. Tokamak is another
type of plasma confinement, which twists magnetic field
by producing current inside of plasma. This success made
tokamak device a main trend in fusion research and
development. This trend has continued until now. The
plasma confinement and its temperature have improved.
Then, in the 1980s, large constructions of tokamak had
begun such as JT-60 (Japan), TFTR (US) and JET (EU).
As for stellarator (also called as Helical device), it also had
started constructions of large devices such as LHD (Japan)
in the 1990s. As another technology for fusion power,
inertial confinement fusion has to be described. Inertial
confinement is different from magnetic confinement as
tokamak or helical devices. To make fusion reaction, it
uses ultra-high-power laser to compress and heat up fuel
at the condition where fusion reaction is possible. In this
paper, although we are not going through the helical
device and inertial fusion device, recent development for
laser fusion has been also significant.
ITER (International Thermonuclear Experimental
Reactor) project is now in progress. ITER will be the first
fusion device to produce net energy. And ITER will be the
first fusion device to test the integrated technologies,
materials, and physics regimes necessary for the
commercial production of fusion-based electricity
9)
.
Thousands of engineers and scientists have contributed to
the design of ITER since the idea for an international joint
experiment in fusion was first launched in 1985. The
ITER MembersChina, the European Union, India,
Japan, Korea, Russia and the United Statesare now
engaged in a 35-year collaboration to build and operate
the ITER experimental device, and together bring fusion
to the point where a demonstration fusion reactor can be
designed. It is now under construction in southern France
and will start operation around 2025. The main targets of
ITER specified to: (1) Produce 500 MW of fusion power,
(2) Demonstrate the integrated operation of technologies
for a fusion power plant, (3) Achieve a deuterium-tritium
plasma in which the reaction is sustained through internal
heating, (4) Tritium test breeding and (5) Demonstrate the
safety characteristics of a fusion device. The ITER reactor
will have diameter of 30m and height of 25m (see Fig. 1).
This size is much larger than a conventional fission reactor
and any other fusion tokamak device that has been built
ever. Therefore, the construction itself is a challenging
task. ITER will test the feasibility of fusion power plant.
Japan as a member of ITER has been a leading country in
technological aspects. Many parts and methods for ITER
have been designed and manufacturing by institutes and
companies in Japan.
4. Nuclear Fusion Trend in Japan
Fusion energy trend in Japan will be presented. In the
priority plan of government, there are 4 fields in nuclear
fusion development: (1) Tokamak plan, (2) LHD (Large
Helical Device) plan (3) Laser scheme fusion (4) Furnace
engineering
10)
. Although tokamak is the most developed
technology, other method of fusion energy is necessary to
expand the diversity and alternatives. Especially in helical
device, we have a large experimental device called LHD
in Toki, Gifu prefecture. Its technique how to confine
plasma is similar to tokamak configuration, in terms of
making use of magnetic field. Then, research and
technology interactions between them are actively
- 18 -

EVERGREEN Joint Journal of Novel Carbon Resource Sciences & Green Asia Strategy, Vol. 04, Issue 04, pp. 16-23, December 2017
conducted. Furnace engineering is also important from the
viewpoint of fundamental research. As one country, to
design a prototype reactor is highly important because one
must have its own design of nuclear fusion reactor. Based
on the knowledge and technology for ITER, Japan has
started its own prototype reactor designing.
Fusion energy is one of energy policy in Japan. The
importance of energy policy has been intensively
discussed year by year. There are several fields in
Japanese energy policy, for example, fuel cell, hydrogen
energy and renewable energy. The importance index by
technological sectors in Japan is shown in Fig. 2 (A)
11)
.
Fusion energy is an important issue in the third. The
notable difference between fusion energy and other energy
resources is that fusion power is not still available. In
another word, government assistance is necessary for the
further development. In some fields such as renewable
energy or fuel cell, private companies have already
entered into whole system production. However, nuclear
fusion power has not been commercialized. In Fig. 2 (B)
11)
,
the need for government involvement in different fields is
shown. For fusion energy, it shows that the Japan
government considers its involvement in this field is
indispensable.
Nuclear fusion is regarded as one important issue on
energy policy in Japan. The next question is how much
budget is practically spent on the research and
development of nuclear fusion. Figure 3 illustrates the
itinerancy of national budget on fusion sector from 1971
to 2007
12)
. The amount of budget has been decreasing
since 1997. One of the reasons of decreasing budget is
clearly the stall of the Japanese economy. Another reason
is that a large construction of LHD at Toki finished around
1998. Therefore, the budget after the construction has
been used mainly for the running cost of those huge
equipment. Along with the reduction of budget, working
population in this field has been also decreasing.
According to a report by Japan Atomic Industrial Forum
12)
,
it says that R & D of fusion energy has been supported
only by the government, therefore, it highly depends on
national budget from the viewpoint of the market.
Earnings of companies in this field basically keep
decreasing. It also mentions that since the developments
of large experimental devices are always single orders and
long-term, inheritance of technology should be difficult.
Development such fusion energy has to be a long-term
national project, however, companies have to take risks to
Fig. 1. ITER Tokamak Design
9)
Clean use of fossil resources
Fuel cell
Fusion energy
Innovative nuclear system
Resource reuse
Distributed energy system
Energy conversion efficiency
Hydrogen energy system
Renewable energy
Resource assessment
All
(A)
Innovative nuclear system
Fusion energy
Hydrogen energy system
Fuel cell
Distributed energy system
Renewable energy
Clean use of fossil resources
Energy conversion efficiency
Resource assessment
Resource reuse
La rg e M iddle Small None
Fig. 2. A) The importance index by technological sectors in Japan
11)
, B) The need for government
involvement in energy policy in Japan
11)
(B)
- 19 -

Citations
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Abstract: The objective of this paper is to investigate how electrical resistivity changes as electromagnetic waves penetrate deep into the subsurface of Lili-Sepporaki geothermal prospect, using Magnetotelluric data. Lili Sepporaki is an andesitic-trachytic volcanic-rich area located in western Sulawesi-Indonesia. Magnetotelluric data was processed using SSMT2000 and MTEditor software programmes. Results show that resistivity of rocks generally increases with decreasing frequency, that is; less than 100 Ohm-m for frequencies greater than 100 Hertz; and fluctuates between 100 -1000 Ohm-m for frequency range 10.1 Hertz. Resistivity also increases with depth of penetration of electromagnetic waves. Weathering, hydrothermal alteration, and many times fluids increase the conductivity of rocks. A low resistivity anomaly is seen around the hot spring, northwards. Presence of fluids in an intensively fractured volcanic rock lowers its resistivity. In the future, another Magnetotelluric sounding should be carried with much more measurement stations followed by a three-dimensions interpretation.

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References
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Journal ArticleDOI
Abstract: The basic concepts of the controlled thermonuclear program at Project Matterhorn, Princeton University are discussed. In particular, the theory of confinement of a fully ionized gas in the magnetic configuration of the stellarator is given, the theories of heating are outlined, and the bearing of observational results on these theories is described.Magnetic confinement in the stellarator is based on a strong magnetic field produced by solenoidal coils encircling a toroidal tube. The configuration is characterized by a ``rotational transform,'' such that a single line of magnetic force, followed around the system, intersects a cross‐sectional plane in points which successively rotate about the magnetic axis. A theorem by Kruskal is used to prove that each line of force in such a system generates a toroidal surface; ideally the wall is such a surface. A rotational transform may be generated either by a solenoidal field in a twisted, or figure‐eight shaped, tube, or by the use of an additional transverse multipolar helical field, with helical symmetry.Plasma confinement in a stellarator is analyzed from both the macroscopic and the microscopic points of view. The macroscopic equations, derived with certain simplifying assumptions, are used to show the existence of an equilibrium situation, and to discuss the limitations on material pressure in these solutions. The single‐particle, or microscopic, picture shows that particles moving along the lines of force remain inside the stellarator tube to the same approximation as do the lines of force. Other particles are presumably confined by the action of the radial electric field that may be anticipated.Theory predicts and observation confirms that initial breakdown, complete ionization, and heating of a hydrogen or helium gas to about 106 degrees K are possible by means of a current parallel to the magnetic field (ohmic heating). Flow of impurities from the tube walls into the heated gas, during the discharge, may be sharply reduced by use of an ultra‐high vacuum system; some improvement is also obtained with a divertor, which diverts the outer shell of magnetic flux away from the discharge. Experiments with ohmic heating verify the presence of a hydromagnetic instability predicted by Kruskal for plasma currents greater than a certain critical value and also indicate the presence of other cooperative phenomena. Heating to very much higher temperatures can be achieved by use of a pulsating magnetic field. Heating at the positive‐ion cyclotron resonance frequency has been proposed theoretically and confirmed observationally by Stix. In addition, an appreciable energy input to the positive ions should be possible, in principle, if the pulsation period is near the time between ion‐ion collisions or the time required for a positive ion to pass through the heating section (magnetic pumping).

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01 Jun 2010-Energies
Abstract: Fifty years ago, the secrecy surrounding magnetically controlled thermonuclear fusion had been lifted allowing researchers to freely share technical results and discuss the challenges of harnessing fusion power. There were only four magnetic confinement fusion concepts pursued internationally: tokamak, stellarator, pinch, and mirror. Since the early 1970s, numerous fusion designs have been developed for the four original and three new approaches: spherical torus, field-reversed configuration, and spheromak. At present, the tokamak is regarded worldwide as the most viable candidate to demonstrate fusion energy generation. Numerous power plant studies (>50), extensive R&D programs, more than 100 operating experiments, and an impressive international collaboration led to the current wealth of fusion information and understanding. As a result, fusion promises to be a major part of the energy mix in the 21st century. The fusion roadmaps developed to date take different approaches, depending on the anticipated power plant concept and the degree of extrapolation beyond ITER. Several Demos with differing approaches will be built in the US, EU, Japan, China, Russia, Korea, India, and other countries to cover the wide range of near-term and advanced fusion systems.

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Journal ArticleDOI
01 Sep 2020
Abstract: The objective of this paper is to investigate how electrical resistivity changes as electromagnetic waves penetrate deep into the subsurface of Lili-Sepporaki geothermal prospect, using Magnetotelluric data. Lili Sepporaki is an andesitic-trachytic volcanic-rich area located in western Sulawesi-Indonesia. Magnetotelluric data was processed using SSMT2000 and MTEditor software programmes. Results show that resistivity of rocks generally increases with decreasing frequency, that is; less than 100 Ohm-m for frequencies greater than 100 Hertz; and fluctuates between 100 -1000 Ohm-m for frequency range 10.1 Hertz. Resistivity also increases with depth of penetration of electromagnetic waves. Weathering, hydrothermal alteration, and many times fluids increase the conductivity of rocks. A low resistivity anomaly is seen around the hot spring, northwards. Presence of fluids in an intensively fractured volcanic rock lowers its resistivity. In the future, another Magnetotelluric sounding should be carried with much more measurement stations followed by a three-dimensions interpretation.

4 citations


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In this paper, the authors focus on technological aspects to solve the expected energy crisis in near future and discuss the research and technical trend in nuclear fusion.